Anthony Joshua lost about £15m after his defeat by Oleksandr Usyk at Tottenham Hotspur stadium on Saturday night.
According to a report by Totalsportal.com, Anthony Joshua had £10m guaranteed, plus a share of PPV sales.
However, the fighter lost £15m potential earnings following his defeat.
On his part, Usyk pocketed an estimated £5m for the Joshua fight.
Anthony Joshua’s reign as world boxing heavyweight champion ended on Saturday, with the proposed ‘Battle of Britain’ against Tyson Fury now in tatters.
This was after Oleksandr Usyk of Ukraine claimed a stunning unanimous decision win at Tottenham Hotspur Stadium in London
Usyk had given up three inches in height and four in reach, as well as nearly 20 pounds in weight, for this fight.
But the former undisputed world cruiserweight champion’s technical acumen came to the fore in an electric atmosphere.
Joshua finished the bout slumped against the ropes as his smaller foe looked for a dramatic finish.
And, as it was not forthcoming, Usyk claimed the WBA, IBF and WBO titles after he was given the nod by all the three judges.
Scores of 117-112, 116-112 and 115-113 were just reward after a near-masterclass from the unbeaten Usyk.
He became only the third fighter after Evander Holyfield and David Haye to win world titles at cruiserweight and heavyweight.
Joshua was obligated to face WBO mandatory challenger Usyk after a bout against Fury fell through earlier this year.
He appeared philosophical in accepting the result when the scores came as he suffered the second defeat of his career.